1. Field of the Invention
The present invention relates to a developer recovering mechanism which recovers developer within a developing unit to a developer cartridge installed in the developing unit, and to an image forming apparatus, and, in particular, to a developer recovering mechanism used in a rotary-type developing apparatus which rotates plural developing units and successively moves them to a developing region, and to an image forming apparatus provided with this developer recovering mechanism.
2. Description of the Related Art
Among conventional image forming apparatuses, there is known a type which is provided with a rotary-type developing apparatus in which plural developing units, which house toners of different colors, are disposed along a peripheral direction, and these developing units are rotated by a rotor so as to successively be moved to a developing region which opposes a photosensitive body. Such an image forming apparatus is structured such that, for example, four developing units housing toners of the respective colors of yellow, magenta, cyan, and black are moved successively to the developing region, toner images of the four colors are successively formed on the photosensitive body, and the toner images of the four colors are superposed on one another on a recording medium or an intermediate transfer body such that a color image is formed.
A developer cartridge is removably disposed at each of the developing units. The developer cartridge, for example, replenishes new developer to the interior of the developing unit, and recovers the developer which is within the developing unit.
A recovery opening for recovery of the developer within the developing unit is provided at an end surface of the developer cartridge. One end of a film-shaped member is fixed and supported at this end surface in which the recovery opening is formed. A weight is attached to the other free end of the film-shaped member, and this free end opens and closes the recovery opening.
At the time when the developing units are successively moved by rotation of the rotor, when the recovery opening is positioned beneath a supporting portion of the film-shaped member, the film-shaped member closes the recovery opening. On the other hand, when the recovery opening is positioned above the supporting portion of the film-shaped member, the film-shaped member flexes due to the gravity of the weight, and the recovery opening is opened. The developer within the developing unit is then recovered to the developer cartridge from the recovery opening which has been opened (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 10-198144).
However, in the developer cartridge disclosed in this JP-A No. 10-198144, in order to fix and support the film-shaped member, a plate member is attached by being press-fit and welded to an end surface from above the film-shaped member. There are therefore the problems that the manufacturing processes are complex and the manufacturing costs are high.
Further, the recovery opening is opened and closed by the gravity of the weight which is attached to the film-shaped member. Therefore, there are the problems that, even when the recovery opening is closed, it is easy for the film-shaped member to flex, and it is easy for the developer to flow backwards into the developing unit from a gap between the recovery opening and the film-shaped member.